A thin film transistor (TFT) substrate (or referred to as a TFT glass) is one of basic components and one of key basic materials of an LCD. The TFT substrate is a glass substrate, and the glass substrate is a thin glass sheet whose surface is extremely flat. In a process of manufacturing an LCD panel, a transparent conducting layer, that is, an indium tin oxide (ITO) film layer, is deposited by evaporation on a surface of the glass substrate, and transparent conducting patterns are formed by means of photolithography, where these patterns include a pixel pattern and a pattern of an outer lead.
Typically, after manufacture of a complete TFT substrate is completed, the TFT substrate is cut into multiple TFT substrates of a specified size. For example, currently, a prior-art substrate at a highest stage of a fifth-generation lead has a size of 1200*1300 millimeters (mm), and can be cut into six substrates for use of a 27-inch wide-screen television. However, at present, detection for the TFT substrate is mainly performed after the cutting, and is generally performed by detection personnel using an automatic optic inspection (AOI) optical device (for example, a microscope). By means of this method, a small crack or chip occurring in a cut edge of a TFT substrate in a cutting process can be detected.
However, the foregoing detection method is mainly implemented depending on manual detection, detection efficiency is low, and a detection omission may further occur. Moreover, in the foregoing detection method, only the small crack or chip occurring in the cutting process can be detected, a crack or chip occurring in a process in which the TFT substrate is used to assemble an liquid crystal module (LCM) or a transportation process cannot be detected, and a crack or chip occurring in a process in which the LCM is used to assemble a complete device (for example, assemble a television or a mobile phone) cannot be detected, either.